This contract is for the development of monoclonal antibodies to polymorphic tissue specific antigens which may play an important role in graft rejection. The contractor will use classical immunization, fusion and screening techniques to derive and characterize monoclonal antibodies to tissues from heart and other organs. In addition the contractor will use monomorphic monoclonal antibodies developed under a prior contract to precipitate antigens from crude whole organ preparations and use this precipitate to immunize mice in the hope of producing monoclonal antibodies to polymorphic antigens which are transplant relevant.